There has been continuing interest in organic materials which can function as flavoring agents for modifying or improving the flavor and aroma of tobaccos, foodstuffs, beverages and other such consumer products.
It has been established that alkylpyrazines are natural components of tobacco smoke, and that they most probably are important contributors to tobacco smoke flavor [A. Baggett et al, J. Chromatog, 97, 79 (1974)]. Further, it has been disclosed in the patent literature that addition of alkylpyrazines to tobacco results in an improvement in the flavor of smoking compositions as perceived by a test panel.
British Pat. No. 1,244,068 describes a method for influencing the smoke flavor of tobacco or a tobacco mixture which consists of treating the tobacco with a pyrazine derivative of the following chemical structure: ##STR2## in which each R is independently a hydrogen atom, an aliphatic radical, an alicyclic radical or an aromatic hydrocarbon radical, such radicals having up to 9 carbon atoms, or R is a heterocyclic radical containing 4 to 9 carbon atoms.
U.S. Pat. No. 3,402,051 describes a process for imparting a popcorn-like flavor and aroma to tobacco and foodstuffs by the incorporation of a 2-acetylpyrazine derivative therein.
Other patents which disclose the addition of various pyrazine compounds to tobacco and foodstuffs as a means of providing flavor or flavor enhancement include U.S. Pat. Nos. 3,684,809; 3,705,158; 3,754,934; 3,764,349; 3,767,426; and 3,881,025.
U.S. Pat. No. 3,914,227 discloses pyridyl and pyrazyl ketones and their use in altering the organoleptic properties of tobacco and foodstuffs, and U.S. Pat. No. 4,166,869 discloses acylpyrimidines useful as flavorants for the same type of applications.
Alkylpyridines have also been found to be useful tobacco additives. As an example, U.S. Pat. No. 3,625,224 describes the use of methylpyridines, ethylpyridines and various dialkylpyridines as tobacco additives. U.S. Pat. No. 3,381,691 discloses 2-methyl-5-isopropylpyridine as a tobacco additive.
It is characteristic of pyridine, pyrazine, pyrimidine and other heterocyclic derivatives employed as tobacco flavorants in the prior art, as illustrated by the above described technical literature, that the respective heterocyclic derivatives have the disadvantage of both high volatility and low odor threshold. Both of these properties significantly restrict the extent that these heterocyclic derivatives can be utilized as flavorants in tobacco compositions. A quantity of a pyrazine or pyridine derivative in a tobacco composition sufficient to have a noticeable effect in low delivery cigarettes causes a marked pack aroma.
In a similar manner, the incorporation in tobacco of flavorants in the form of clathrates has been found to be unsatisfactory, since the yield of flavor when tobacco containing such clathrates is burned is very low. Likewise, the yield of flavorant is low when an ester such as menthyl succinate or menthyl borate is incorporated into a tobacco composition that is subsequently burned.
When an aldehyde flavorant such as cinnamaldehyde is added to a smoking composition, the loss of the flavorant during the manufacturing process and during storage is high, due to the relatively high vapor pressure of the aldehydic compound.
Further, as described in U.S. Pat. No. 3,782,391 alkyl esters of beta-methyl valeric acid are known to impart a fruity, apple-like aroma and a nut-like flavor when incorporated in tobacco. However, as noted in U.S. Pat. No. 3,854,485, such flavorant compounds are relatively valuable substances with a low odor threshold, and they present an evaporation problem in prolonged storage of the flavored tobacco compositions. Other esters such as monoalkyl and dialkyl malonates are known to provide a tobacco smoke with a fermented apple-peel and walnut-like flavor and aroma, but such esters yield only a limited form of flavor enhancement in tobacco products.
U.S. Pat. No. 4,036,237 endeavors to overcome some of the disadvantages of the above-described flavorant technology. The said patent provides for the incorporation in smoking compositions of a flavorant compound which imparts cherry-like or fruity flavor to the smoke thereof, which flavorant compound is not lost during the manufacture and storage of the flavored smoking composition, and which is readily released when the smoking composition is burned. Illustrative of a U.S. Pat. No. 4,036,237 flavorant compound is ethyl 2,2-dimethyl-3-hydroxy-3-phenylpropionate.
There remains a need for smoking compositions with enhanced flavor and aroma that do not exhibit the various disadvantages of prior art smoking compositions which contain a relatively volatile compound as a flavorant additive.
Accordingly, it is a main object of this invention to provide tobacco and non-tobacco smoking compositions which have incorporated therein a flavorant additive which is characterized by low volatility and low pack aroma.
It is another object of this invention to provide smoking compositions of tobacco and non-tobacco materials, and blends thereof, containing a heterocyclic-hydroxy-substituted carboxylate flavorant additive, which smoking compositions are adapted to impart flavor and aroma to the mainstream and sidestream smoke under smoking conditions.
It is a further object of this invention to provide novel heterocyclic-hydroxy-substituted carboxylate compounds which can be subjected to pyrolysis conditions to release heterocyclic and carboxylic constituents which can enhance the flavor and aroma of smoking compositions and foodstuffs.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.